Folifer® (Bialport — Produtos Farmacêuticos, S.A., Portugal) is available in film-coated tablet form, each tablet consisting of a central core, containing approximately 90 mg of iron (as ferrous sulfate granules), and 1 mg of folic acid. For comparison purposes, Ferroliver® (SM Pharma

c.a., Venezuela) was used, another iron-containing supplement in tablet form. Ferroliver® contains slightly more iron (99 mg, as ferrous fumarate) compared with Folifer® and a different amount of folic acid (400 μg), as well as containing other compounds, Wee1 inhibitor including 0.0005 mg of vitamin B12 and 1 mg of copper sulfate. Reagents and Solutions The following reagents and solutions were used: concentrated hydrochloric acid 35–37% (Sigma), iron sulfate (II) [Merck], concentrated sulfuric acid 95–97% (Merck), sodium hydroxide (Sigma), monopotassium phosphate (Merck), ammonium sulfate (Merck), cerium (Merck), potassium iodide (Sigma), sodium thiosulfate (Merck), soluble starch (Sigma), and mercuric iodide (Sigma). The reagents and solutions were prepared as follows: Solution of ammonium sulfate and 0.1 M cerium: 65 g of ammonium sulfate and cerium was dissolved and mixed with 30 mL of concentrated sulfuric acid and 500 mL of water. The mixture was cooled and a further 1000 mL of water was added. Then, 25 mL of ammonium sulfate and cerium was added to 2 g of potassium iodide and 150 mL of water. This was

titrated immediately QNZ in vivo with 0.1 M sodium thiosulfate, using 1 mL of starch solution as an indicator. Solution of ammonium sulfate enough and 0.01 M cerium: 50 mL of ammonium sulfate and 0.1 M cerium was diluted with 500 mL water. Starch solution: 1.0 g of soluble starch was ground with 5 mL of water and poured, stirring constantly, into 100 mL of boiling water, to which 10 mg of mercuric iodide was added. Gastric juice (pH 1.5): 90 mL of concentrated hydrochloric acid and 84 mL of 10 M sodium hydroxide were transferred to a 10 L container. This mixture was stirred, and

approximately 9 L of water was added until the pH reached 1.50 ± 0.05. The solution was then made up to 10 L with water. Intestinal juice (pH 4.5): 8.7 g of monopotassium phosphate was added to a 10 L container. Water was added to the mixture, which was stirred and diluted to 1 L. 38 mL of 10 M sodium hydroxide and 30 mL of concentrated hydrochloric acid were then added. The solution was stirred and adjusted until the pH was 4.50 ± 0.05. The solution was then made up to 10 L with water. Intestinal juice (pH 6.9): The same procedure was used as described in preparation of the intestinal juice pH 4.5, except the pH was adjusted to 6.90 ± 0.05. Equipment Weighing was carried out using a Mettler Toledo XS205 balance. The dissolution tests were carried out using the Vankel VK700 dissolution testing station, while the titrimetric determination of iron was evaluated using a Radiometer TIM800 automatic titrator.